The overhead crane is widely used as a carrying tool in the machine manufacturing sector and is composed of an I-beam as its main structural body, which is driven by an alternating current motor to travel along a fixed rail and is provided with a hooked portion having a motor-driven hoisting mechanism for moving articles. The occupational accidents involving the operation of the overhead crane often result from the lack of familiarity with operational procedures on the part of the overhead crane operator. In other words, the occupational safety can be enhanced by a training program in which the operators of the overhead crane are trained to operate the overhead crane by means of an overhead crane simulator. The overhead crane simulator is capable of duplicating artificially the conditions likely to be encountered with by the operator in the course of actual operation of the overhead crane. In addition, the operators are taught to develop an ability to avert the accidents and to cope with the operational problems.
The fixed overhead crane simulator must be used in conjunction with a locomotion platform for the trainee to stroll thereon. The conventional locomotion platform simulator was disclosed in IEEE Proceedings of VRAIS, 1996, pp 60-65. It is not effective and is therefore not well accpeted. In other words, there is no workable locomotion platform available in the market place today.
As far as the simulation technology is concerned, the research and the development of the fixed overhead crane simulator are not much different from those of the movable overhead crane simulator. The operator must stroll on the locomotion platform to operate the overhead crane, thereby involving a number of problems as to the interface of machine and operator, as well as the walking pattern. In the practical operation of the overhead crane or in the license test of the overhead crane operation, the operator is required to walk along a closed path. For this reason, the two dimensional planar motion is the most important element that must be taken into consideration in designing a locomotion platform.
In addition, the more important thing is to design an interface circuit of high speed communication to attain the transmission of the walking data. The variation in the visual landscape and the interactive relationship are completed via changing the control parameters based on the computation of the walking data.
As fas as the movable overhead crane simulation training system, the fixed overhead crane simulation training system, or any other type of simulation training system is concerned, the simulation technology is the development guideline. It is therefore necessary to have a strong interactive relationship to achieve the effect of simulation. As shown in the following table, when the screen redrawing rate 60 frames per second, the response time is so prolonged as to delay the completion of the frame redrawing in light of the cumbersome mathematical calculation of the simulation software and the data inputting/outputting. As a result, the frame redrawing rate is reduced to result in the interruption in the simulative landscape, which leads to a distortion of the actual landscape.
______________________________________ Sampling Communication Processing Redaw ______________________________________ ##STR1## ______________________________________
The above table is indicative of the fact that the frame redrawing rate of 60 frames per second can be attained only when the signal detection, the signal transmission, the computer memory, and the display device are effectively improved. For this reason, the efforts were made by the inventors of the present invention on the research of the high speed communication interface under the virtual circumstance, by using 10 ms as the signal redrawing rate of the locomotion platform.
The main functions of the locomotion platform of the present invention are as follows:
1. attaining the two dimensional planar motion within an effective area.
2. The operator is not required to wear any device except helmet.
3. The facilities can be safely used by the operator without using both hands.
4. The platform is capable of reacting instantly to the walking signal of the operator.
5. The redraw rate of the signal of the locomotion platform is 10 ms.
6. The operator can engage in two dimensional walking motion of 360 degrees.